Cameras equipped with a lens shutter and cameras equipped with a focal-plane shutter are well-known.
A camera equipped with a lens shutter is adapted for flash photography because of the feature of the shape of the shutter opening. On the other hand, the lens of a camera having a focal-plane shutter can be easily replaced because of the feature of the light-blocking structure. Also, the latter camera enables high-speed time control because of the characteristics of the operation.
In an attempt to combine the features of the aforementioned two cameras, an interchangeable lens which has a lens shutter operating alone inside a camera equipped with a focal-plane shutter has been proposed.
The present applicant has already proposed a camera equipped with a lens shutter and a focal-plane shutter for performing a programmed exposure operation and a diaphram-adjusting operation. The camera further includes a selector means for establishing either a lens shutter mode or a focal-plane shutter mode, a first driving means, a second driving means, and a sequential control means. In the lens shutter mode, the lens shutter is operated as a programmed shutter. In the focal-plane shutter mode, the shutter speed and the aperture are controlled by the focal-plane shutter and the lens shutter, respectively. The first driving means controls either the programmed exposure value of the lens shutter of the aperture value or both. The second driving means controls the time for which the focal-plane shutter is operated. The sequential control means controls the timing at which the two driving means are activated.
In the focal-plane shutter mode, when plural photographs are taken in succession with multiple exposure, a clutch mechanism is needed to select either the cocking of the focal-plane shutter or the winding of the film, so that the focal-plane shutter is cocked for every exposure. This necessity arises from the fact that a single motor is generally used to cock the focal-plane shutter and to wind up the film. Conversely, to omit the clutch mechanism, two motors are necessary. Thus, the structure of this camera system has problems. As shown in FIG. 8, since the focal-plane shutter is cocked for every exposure, the next exposure is not enabled during the time T2 for which the shutter is cocked. Consequently, it is impossible to take photographs in succession at a high speed with multiple exposure.